Playing ball with improved shock absorption and anti-rebound capabilities

Abstract

The invention relates to a single-material metallic playing ball (1), comprising a rigid spherical outer shell (2) delimiting a hollow internal volume. The ball further comprises at least one hollow spherical rigid inner shell (3) located in said hollow internal volume, the shells (2, 3) being spaced apart and connected to each other by elastically deformable connecting elements (4) located in the at least one space (V0) between shells and configured so that, in the absence of impact, the shells (2, 3) are concentric and the center of gravity of the ball (1) is located at the center of the ball (1), and upon impact, at least a portion of the connecting elements (4) deform elastically to then allow a displacement of the at least one inner shell (3) relative to the outer shell (2) and thus cushion the impact. Figure to be published with the abstract: Figure 1.

Description

Title of the invention: Playing ball with improved shock absorption and anti-rebound capabilities

[0001] The present invention relates to the technical field of playing balls, such as pétanque balls, Lyonnaise balls, etc., and relates more particularly to a playing ball with improved shock absorption and anti-rebound capabilities.

[0002] When playing pétanque, for example, a player may have to aim at an opponent's ball with his own to make it leave the playing area. Ideally, he should make a square on the spot by throwing his ball at the targeted ball and replacing the latter with his own, that is to say that his ball should practically not move after the impact on the targeted ball.

[0003] During this shot, it is important that the rebound phenomena are as minimal as possible to limit any unpredictable behavior and to ensure as complete a transfer of kinetic energy as possible from the shot ball to the targeted ball.

[0004] Similarly, when the player seeks to place his ball as close as possible to the jack, it is desirable that his ball is not deflected upon impact with the ground and that it bounces as little as possible in order to remain as close as possible to the point of the first bounce. Thus, limiting the rebound phenomenon is sought by both the shooter and the pointer.

[0005] To limit the rebound phenomenon of a hollow metal petanque ball, it is proposed in French patent application FR2638375 to machine, on the internal surface of the two hemispherical shells forming the ball after assembly, grooves constituting either a network of circles parallel to each other, or two networks of circles orthogonal to the crossing points, in a manner analogous to the terrestrial parallels and meridians.

[0006] However, this solution does not allow the rebound to be limited in a sufficiently uniform manner. Indeed, since the thickness of the wall is reduced at the level of the grooves, the rebound is limited when the impact takes place at this level. However, there remain areas where the thickness of the ball is not modified and there is no obstacle to the propagation of the shock wave in the material constituting the ball; the rebound therefore remains significant and the behavior of the ball on impact remains random.

[0007] In order to make the behavior of any ball less unpredictable after bouncing on the ground or hitting another ball, it was proposed in French patent FR2748669 to provide, on the internal face of the two hemispherical shells forming the ball after assembly, protruding patterns consisting of independent ribs arranged only on all or part of the meridians.

[0008] However, the material constituting the shells remains homogeneous and continues to conduct the shock wave, due to a rebound, in an identical manner to a standard ball, with the imperfect contribution of the ribs which only disturb the radial waves. Thus, this solution does not make it possible to limit the rebound in a sufficiently homogeneous manner and the behavior of the ball upon impact remains random.

[0009] Therefore, the prior art solutions proposed for petanque balls still have drawbacks and improvements are possible.

[0010] Providing a solution to these problems appears to be even less easy if it is required that the ball to be played be metallic and made of a single material, which is currently the practice for pétanque balls, for example.

[0011] The aim of the invention is therefore to propose a single-material metallic playing ball whose internal structure maximizes shock absorption and minimizes rebound, while being easy to produce.

[0012] Thus, the present invention relates to a single-material metallic playing ball, the ball comprising a rigid spherical outer shell delimiting a hollow internal volume, characterized in that the ball further comprises at least one hollow spherical rigid inner shell located in said hollow internal volume, the shells being spaced apart and connected to each other by connecting elements located in the at least one space between shells, each connecting element being elastically deformable, the connecting elements being configured so that, in the absence of impact on the ball, the shells are concentric and the center of gravity of the ball is located at the center of the ball, and upon impact on the ball, at least a portion of the connecting elements, in other words at least some of the connecting elements, deform elastically to then allow a displacement of the at least one inner shell relative to the outer shell and thus cushion the impact.

[0013] Of course, the expression "deform elastically" means that the connecting elements which deform do so within their plastic limits, in other words while remaining within their elastic domains.

[0014] It will therefore be understood that the solution according to the present invention makes it possible to obtain a playing ball having improved shock absorption and anti-rebound capabilities, while advantageously remaining compliant with the specifications of the International Pétanque Federation.

[0015] In particular, the specific internal structure of the ball according to the present invention, integrating the connecting elements and the at least one inner shell, makes it possible to reduce the rebound rate, namely the ratio of the exit speed of the ball after impact to the entry speed of the ball before impact. For example, depending on the type of connecting elements, the thicknesses of the walls of the shells and the post-treatment carried out on the ball after its production, it is possible to reduce this rebound rate significantly, at least by more than 30% compared to a classic pétanque ball.

[0016] By single material it is understood that the outer shell, the at least one inner shell and the connecting elements are made of a single material.

[0017] Preferably, each connecting element is elastically deformable at least along a radial direction of the outer shell. The term "radial direction" means any direction carried by a straight line segment connecting the center of the outer shell to its circumference. The connecting elements may, if appropriate, themselves be radial elements, namely elements which have a longitudinal dimension which is carried by a radial direction.

[0018] Alternatively, each connecting element may be elastically deformable in at least two spatial directions, which preferably include a radial direction of the outer shell. These spatial directions correspond in particular to the conventional directions of movement of the six degrees of freedom in mechanics, namely deformations (traction, compression) along three perpendicular axes and deformations (torsion, bending) around these three axes.

[0019] Preferably, the connecting elements are spaced apart from each other, and distributed, preferably regularly distributed, in the at least one space between shells, all around the shell located inside.

[0020] The connecting elements may not be distributed regularly in the at least one space between shells, in other words no regular implantation pattern of the connecting elements can be extracted from this distribution.

[0021] Preferably, the connecting elements are regularly distributed all around the inner shell. In other words, the connecting elements are arranged according to one or more implantation patterns. For example, the connecting elements can be implanted uniformly, namely that the angular distance between two neighboring connecting elements is identical for all the connecting elements, and / or symmetrically according to one or more symmetries, for example with respect to the equatorial plane of the outer shell, and / or in groups of connecting elements with the groups distributed regularly, etc.

[0022] The connecting elements may or may not be identical.

[0023] Preferably, the connecting elements are constituted by silentblocs or hollow bodies with a corrugated or accordion structure or solid or hollow rods. It will be understood that, whatever the type of connecting element chosen, as well as its geometric shape and its dimensions, each connecting element will be capable of deforming elastically and within its plastic limit when the ball undergoes a shock, in particular during an impact with the ground, so as to allow a displacement of the at least one inner shell relative to the outer shell with a slight time lag and a different movement speed.

[0024] According to a particular embodiment, each hemisphere of the ball comprises ten connecting elements in the at least one space between shells, namely one connecting element at the pole, three connecting elements arranged at a first distance from the pole and six connecting elements arranged at a second distance from the pole which is greater than the first distance, said six connecting elements at the second distance being located in the vicinity of the equatorial plane.

[0025] For example, each connecting element may be of circular section and have a diameter of between 2 and 5 mm. The outer shell may have a thickness of between 3 and 5 mm and the at least one inner shell may have a thickness of between 2 and 3 mm.

[0026] For example, the ball comprises an outer shell 76 mm in diameter and 3.5 mm thick and a single inner shell 57 mm in diameter and 2.7 mm thick, and therefore connecting elements each having a length in the radial direction of 6 mm.

[0027] It will be understood that the dimensions of the connecting elements and the wall thicknesses of the shells may be defined as a function of the diameter of the ball and its mass so that the ball has optimal cushioning. In particular, these dimensions may be calculated on the basis of results of numerical simulations, for example a static simulation of a free fall of the ball, which does not pose a problem for those skilled in the art. These simulations may be supplemented, for example, by free fall tests in real conditions.

[0028] Preferably, the ball is made entirely of steel, in particular stainless steel.

[0029] Advantageously, the ball is made of type 316L stainless steel. This is a type of austenitic stainless steel with a low carbon content having high resistance to corrosion, hot oxidation and fining.

[0030] The ball may further comprise one or more grooves on the external surface of the outer shell.

[0031] For example, the outer shell may have a spiral groove. The arrangement of one or more grooves on the outer surface of the ball allows it to brake and increase its grip on the ground.

[0032] According to a particular embodiment, the ball may be composed of two identical halves assembled together at a joint plane and symmetrical with respect to the joint plane, each half comprising an outer hemispherical half-shell corresponding to half of the outer shell and at least one inner hemispherical half-shell corresponding to half of the at least one inner shell as well as the connecting elements between these half-shells.

[0033] Preferably, the half-shells of one half are assembled to the corresponding half-shells of the other half at the joint plane by gluing. Alternatively, they could be assembled by sintering, by nesting or by welding.

[0034] In order to guarantee the alignment and symmetry of the connecting elements, the joint plane of the two outer half-shells can be broken and have keyholes.

[0035] Preferably, for each half, the half-shells and the connecting elements are formed in one piece. Each half can thus be produced by metal additive manufacturing. Such additive manufacturing makes it possible to obtain balls having relatively complex geometries.

[0036] Alternatively, the half-shells and the connecting elements could be formed separately, in particular by printing, then assembled by gluing. In this case, a housing is provided at each junction zone between a connecting element and a shell wall, which housing is shaped to receive one end of the connecting element.

[0037] Advantageously, the connecting elements are hollow elements and the at least one inner shell comprises, opposite the hollow of each connecting element, a radial through-hole. Such through-holes allow, in the case of manufacturing the ball by 3D printing by powder deposition, the evacuation of powder residues and therefore the optimization of printing performance. Of course, the present invention is not limited to a specific technology, and mention may be made, for example, of the technique known as “MoldJet” (registered trademark) developed by the company Tritone Technologies Ltd.

[0038] Alternatively, the ball is a single-piece, in other words the shells and the connecting elements are in a single piece, without assembly of half-shells. Such a ball can be produced by metal additive manufacturing. The production of a single-piece ball makes it possible to avoid the complex step of assembling the two half-shells and to guarantee perfect aesthetics of the ball obtained, without assembly lines.

[0039] The production of the ball in one piece can be implemented, for example, by an additive manufacturing process by projection of binder on a powder bed called “Metal Binder Jetting”. This process comprises a shaping step consisting of superimposing layers of powders, agglomerated by a polymer binder. The binder is selectively deposited by a print head. This shaping step makes it possible to obtain a “green” part and is followed by a consolidation step by sintering. After burning the binder (debinding), the “green” part is sintered in order to give the part its final density and its mechanical characteristics.

[0040] Advantageously, in order to allow the evacuation of residual powder due to the shaping step, powder evacuation holes are provided through the shells.

[0041] Again, the present invention is not limited to a particular manufacturing process and “MoldJet” technology can again be mentioned as another example of an additive manufacturing process.

[0042] Particular embodiments of the present invention will now be described, with reference to the accompanying drawings.

[0043] In these drawings:

[0044] [Fig-1] is a perspective view of the two halves forming the ball after assembly according to a first embodiment of the invention;

[0045] [Fig.2] is a view of one of the halves of a ball similar to that of [Fig.l], according to the joint plane between said two halves;

[0046] [Fig.3] is a perspective view of a connecting element alone, in a mode in which the connecting element is of the hollow body type with an accordion structure;

[0047] [Fig.4] is a perspective view of one half of the outer hull alone;

[0048] [Fig.5] is a perspective view of an inner shell alone, said inner shell inner, two halves of outer shell according to [Fig.4] and connecting elements according to [Fig.3] being intended to be assembled by gluing to form a ball according to another embodiment of the invention;

[0049] [Fig.6] is a sectional view of a ball according to yet another embodiment of the invention, according to an equatorial plane of the ball;

[0050] [Fig.7] is a view showing the outer face of the ball in a rea ​​mode particular use of the invention; and

[0051] [Fig.8] is a sectional view of a ball according to yet another embodiment of the invention, in which the ball is made in one piece.

[0052] If we first refer to Figures 1 and 2, we can see that a petanque ball 1 is shown there according to a first embodiment of the present invention. The ball 1 is made up of two identical halves 1a, 1b assembled, in particular by gluing, in an equatorial plane P. It is easily understood that after assembly of the two halves 1a, 1b, the ball 1 comprises a hollow spherical outer shell 2, a hollow spherical inner shell 3, and elastically deformable connecting elements 4 interposed between the two shells 2, 3, and connecting them together.

[0053] The outer shell 2 is a spherical shell consisting of two hemispherical outer half-shells 2a, 2b. The outer shell 2 has a spherical outer face whose diameter DI is the diameter of the ball 1 and a spherical inner face delimiting a hollow inner volume. Its thickness E1 is constant. The outer face may be smooth or have one or more grooves 5, as shown in [Fig.7]. For example, the groove 5 may be a continuous spiral groove. In addition, the outer face may bear the manufacturer's label and mark, the weight of the ball and its identification reference. The inner face is smooth, i.e. free of raised patterns or hollow, between the connecting elements 4. In order to avoid any error during the assembly of the two half-shells 2a, 2b, at least one key 6 is advantageously provided at the joint plane 1c. In particular, the circular free edge of each half-shell 2a, 2b comprises a projecting rib 60 and a recess 61 of complementary shape, the rib 60 and the recess 61 of the same half-shell 2a or 2b being diametrically opposed. Once the two half-shells 2a, 2b are assembled, the projecting rib 60 of one of the half-shells fits into the recess 61 of the other half-shell.

[0054] The inner shell 3 is a spherical shell consisting of two hemispherical inner half-shells 3a, 3b. The inner shell 3 has a spherical outer face whose diameter D3 is strictly less than the inner diameter D2 of the outer shell 2 and a spherical inner face delimiting a hollow inner volume. Thus, the inner shell 3 is located inside the outer shell 2, namely in the hollow inner volume of the outer shell 2, and is hollowed out in its center. Its thickness E2 is constant. Thus, a hollow spherical volume V0, called the space between shells, is defined between the shells 2, 3. The outer and inner faces are smooth, namely free of raised or hollow patterns, between the connecting elements 4. The circular free edge of each half-shell 3a, 3b, forming the equatorial plane of the inner shell 3, is flat.In the embodiment shown in Figures 1 and 2, the inner shell 3 comprises a plurality of radial through-holes 7 opening onto the outer and inner faces, each hole 7 being located opposite a connecting element 4.

[0055] In the absence of impact with the ground or with another ball, the outer shells 2 and inner shells 3 are concentric and the center of gravity of the ball 1 is located at the center of the ball 1.

[0056] Alternatively, several inner shells could be provided inside the hollow internal volume of the outer shell 2, each additional inner shell then being received inside another inner shell of larger diameter and connected to the latter by connecting elements 4.

[0057] The inner shell 3 and the outer shell 2 are connected to each other by the plurality of elastically deformable connecting elements 4. These connecting elements 4 are located in the hollow spherical volume V0 defined between the two shells 2, 3 and extend radially. In other words, only the connecting element 4 arranged at a pole extends perpendicular to the joint plane 1c. Each connecting element 4 is an independent element, that is to say that its deformation is independent of the deformation of the other connecting elements 4. In other words, the connecting elements 4 are spaced from each other, except possibly at one of their ends. In the embodiment shown in Figures 1 and 2, each element connecting element 4 is a hollow body of circular section with an accordion structure having a first circular end in contact with the internal face of the outer shell 2 and a second circular end in contact with the external face of the inner shell 3. Each discharge hole 7 opens into the interior of the hollow body. Each half 1a, 1b of the ball 1 comprises ten connecting elements 4, namely one connecting element 4 at the pole, three connecting elements 4 located at a first distance from the pole and six connecting elements 4 located at a second distance from the pole which is greater than the first distance, said six connecting elements 4 at the second distance being located in the vicinity of the equatorial plane P. The connecting elements 4 of the two assembled halves 1a, 1b are symmetrical with respect to the equatorial plane P.

[0058] Alternatively, as can be seen in [Fig.6], each connecting element 4 could be a rod, solid or hollow, connecting the shells 2, 3 together. Such a rod may have a constant cross-section or enlarged end regions, for example conical. The connecting elements 4 could also be constituted by silentblocs (not shown) or any other links capable of deforming elastically and within their plastic limit during an impact.

[0059] Similarly, the number of connecting elements 4 can be variable, even or odd. For example, there could be seventeen connecting elements 4 per half 1a, 1b of ball ([Fig.5]). The position of the connecting elements 4 can also be variable.

[0060] The geometry and dimensions of the connecting elements 4 can also be variable, provided that the shells 2 and 3 are kept concentric before impact and that they deform elastically and within their plastic limit during an impact to allow a displacement of the inner shell 3 relative to the outer shell 2, with a time lag, and thus cushion the impact.

[0061] The outer 2 and inner 3 shells are rigid metal shells, preferably made of stainless steel, more preferably of 316L type stainless steel. The connecting elements 4 are made of the same material as the shells 2 and 3.

[0062] By way of example, the ball 1 may have the following dimensions: an outer diameter DI of the outer shell 2 of 76 mm, a thickness E1 of the outer shell 2 of 3.5 mm, an outer diameter D3 of the inner shell 3 of 57 mm, a thickness E2 of the inner shell 3 of 2.7 mm, connecting elements 4 of 2 to 5 mm in diameter and 6 mm in length. With such dimensions and using type 316L stainless steel, the total weight of the ball 1 may be 650 grams.

[0063] In order to enable the production of complex geometries, the ball 1 according to the present invention, as shown in Figures 1 and 2, is manufactured additively using 3D metal printing, in particular from powder. More particularly, the two halves 1a, 1b of ball 1 can be printed by 3D metal printing and then glued at the joint plane. The evacuation holes 7 provided through the inner shell 3 make it possible to optimize printing performance by allowing the evacuation of powder residues stored in the connecting elements 4 and in the wall of the shells 2, 3.

[0064] If we now refer to Figures 3 to 5, we can see that the ball 1 according to another embodiment of the present invention could also be manufactured by assembling multiple elements, in particular by gluing multiple elements. In particular, each connecting element 4 ([Fig.3]), each outer half-shell 2a, 2b ([Fig.4]) and the inner shell 3 ([Fig.5]) can be produced independently and then assembled by gluing. The production of each of these parts could be done independently of the 3D metal printing. In this manufacturing method, in order to make the assembly less complex, it is appropriate to provide housings 40 for each end of the connecting elements 4 at the outer shell 2 and the inner shell 3, in particular circular housings 40 in the case of connecting elements 4 with circular ends. It is then no longer necessary to provide evacuation holes 7 through the inner shell 3.

[0065] If we now refer to [Fig. 8], we can see that the ball 1 according to yet another embodiment of the present invention could also be manufactured in a single piece, such as for example by the so-called “Metal Binder Jetting” technology. This additive manufacturing process by binder jetting makes it possible to obtain a ball 1 without any assembly step. In this single-piece embodiment, the outer shell 2, the inner shell 3 and the connecting elements 4 are formed in a single piece.

[0066] For this purpose, internal evacuation holes 7 are provided through the inner shell 3 in order to allow the passage of residual powder from the internal volume of the inner shell 3 to the space V0 between the inner shell 3 and the outer shell 2. More particularly, four internal evacuation holes 7, for example 4 mm in diameter, are provided symmetrically through the inner shell 3, three of these holes 7 being visible in [Fig. 8]. In addition, at least one external evacuation hole is provided through the outer shell 2 in order to allow the evacuation of the residual powder located in the space V0 between shells to the outside of the ball 1. In particular, an external evacuation hole (not visible in [Fig. 8]), for example 8 mm in diameter, is provided through the outer shell 2 opposite one of the internal evacuation holes 7 of the inner shell 3.This external evacuation hole is closed by a conical plug (not visible) made of the same material as that of ball 1 and secured to the external shell 2 by gluing or during sintering. The presence of these internal and external evacuation holes is necessary to allow the complete evacuation of any residual material used in phase. printing and not useful in the consolidation phase. In the event that this residual material is not completely removed, it could remain accumulated around singular points inside ball 1 and therefore generate an unbalance of the ball 1 thus obtained.

[0067] Of course, a single-piece ball 1 can be obtained by other manufacturing processes, such as for example “MoldJet” technology (registered trademark), and the present invention is therefore not limited to a particular manufacturing process.

[0068] During a game of boules, when the boule 1 according to the present invention is thrown and comes into contact with the ground or with another boule, it undergoes an impact phase, followed by a crushing phase, a minimal rebound phase and then a release phase.

[0069] Before impact with the ground, the outer shell 2 and the inner shell 3 are perfectly concentric. During the impact phase, the outer shell 2 comes into contact with the ground and transmits to the ground the force due to its speed and its weight, and the inner shell 3 begins to move in the hollow internal volume of the outer shell 2.

[0070] During the crushing phase, the outer shell 2 crushes at its contact zone with the ground. The inner shell 3 continues its movement towards the ground since it is not directly in contact with the ground. The forces transmitted by the inner shell 3 are transmitted with a slight time lag compared to the forces transmitted by the outer shell 2. For example, for the embodiment of the ball 1 whose diameter and thickness dimensions have been indicated above, it can be estimated that the inner shell 3 moves by the order of 10 micrometers and that the time lag is by the order of 10 microseconds.The connecting elements 4 located on the side of the impact zone with the ground undergo a crushing force due to the forces transmitted by the inner shell 3, while the connecting elements 4 located opposite the impact zone undergo a stretching force and the intermediate connecting elements 4 undergo a shear force.

[0071] During the rebound phase, the inner shell 3 ends its movement towards the ground while the outer shell 2 starts its movement away from the ground, in other words its rebound. The forces between the outer shell 2 and the inner shell 3 oppose each other for a short time. This downward movement of the inner shell 3, which is opposed to the upward movement of the outer shell 2, makes it possible to limit the rebound of the ball 1. A cushioning phenomenon then occurs.

[0072] During the final release phase, the outer shell 2 continues its movement away from the ground and leaves the ground. The inner shell 3 then also moves away from the ground. However, the outer shell 2 and inner shell 3 do not rise at the same speed. Indeed, the outer shell 2 rises under the effect of the rebound on the ground while the inner shell 3 rises under the elastic effect of the compressed connecting elements 4 which relax. There is therefore a phase shift in the speeds of movement between the outer shell 2 and the inner shell 3 and an internal oscillation which allows the accumulated kinetic energy to be gradually dissipated.

[0073] These different phases are observed with all of the embodiments described above.

[0074] It is understood that the particular embodiments which have just been described have been given for informational purposes and are not limiting, and that modifications may be made without departing from the scope of the present invention. Thus, the invention is not limited by the number, geometry or position of the connecting elements, nor by the number of internal shells.

Claims

Claims

1. Single-material metallic playing ball (1), the ball (1) comprising a rigid spherical outer shell (2) delimiting a hollow internal volume, characterized in that the ball (1) further comprises at least one hollow spherical rigid inner shell (3) located in said hollow internal volume, the shells (2, 3) being spaced apart and connected to each other by connecting elements (4) located in the at least one space (VO) between shells, each connecting element (4) being elastically deformable, the connecting elements (4) being configured so that, in the absence of impact on the ball (1), the shells (2, 3) are concentric and the center of gravity of the ball (1) is located at the center of the ball (1), and upon impact on the ball (1), at least a portion of the connecting elements (4) deform elastically to then allow movement of the at least one inner shell (3) relative to the outer shell (2) and thus cushion the impact.

2. Ball (1) according to claim 1, characterized in that each connecting element (4) is elastically deformable at least along a radial direction of the outer shell (2).

3. Ball (1) according to claim 1, characterized in that each connecting element (4) is elastically deformable in at least two spatial directions, which preferably include a radial direction of the outer shell (2).

4. Ball (1) according to any one of claims 1 to 3, characterized in that the connecting elements (4) are spaced from each other and distributed, preferably regularly distributed, in the at least one space (VO) between shells, all around the shell (3) located inside.

5. Ball (1) according to any one of claims 1 to 4, characterized in that the connecting elements (4) consist of silent blocks or hollow bodies with a corrugated or accordion structure or solid or hollow rods.

6. Ball (1) according to any one of claims 1 to 5, characterized in that it is made entirely of steel, in particular stainless steel.

7. Ball (1) according to any one of claims 1 to 6, characterized in that it is composed of two identical halves (1a, 1b) assembled together at a joint plane (1c) and symmetrical with respect to the joint plane (1c), each half (1a, 1b) comprising a

8.

9.

10. outer hemispherical half-shell (2a, 2b) corresponding to half of the outer shell (2) and at least one inner hemispherical half-shell (3a, 3b) corresponding to half of the at least one inner shell (3) as well as the connecting elements (4) between these half-shells. Ball (1) according to claim 7, characterized in that for each half (1a, 1b), the half-shells (2a, 3a; 2b, 3b) and the connecting elements (4) are formed in one piece. Ball (1) according to claim 8, characterized in that the connecting elements (4) are hollow elements and that the at least one inner shell (3) comprises, opposite the hollow of each connecting element (4), a radial through-hole (7). Ball according to any one of claims 1 to 6, characterized in that the ball is in one piece.

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